Seasonal Variation of the Solute Content and the Sr87/Sr86 Ratio of the Olentangy and Scioto Rivers at Columbus, Ohio

Author Institution: Department of Geology and Water Resources Center, The Ohio State University, Columbus, Ohio 43210The concentrations of sodium, potassium, calcium, and strontium in water samples collected from the Olentangy and Scioto Rivers at Columbus, Ohio, during 1966, have been determined. The water samples were collected at weekly intervals throughout the year and were combined into four-week composites. The average concentrations, weighted according to discharge, and the ranges of variation for each element in the Olentangy River (in units of Mg/ml) were: Na = 22.3 (16.6 to 38.5), K = 3.3 (2.2 to 4.9), Ca = 72.4 (54.4-101.5), Sr=0.923 (0.604 to 1.73). In the Scioto River the concentrations of these elements were: Na = 12.2 (5.8 to 20.3), K = 3.6 (2.2 to 5.0), Ca = 78.8 (53.2 to 96.2), Sr = 1.91 (0.954 to 2.79). In both rivers the concentrations of sodium and strontium decreased linearly with increasing discharge, whereas the concentrations of potassium and calcium did not. The concentration of potassium increased steadily during the summer and reached a peak in the fall. The Sr87/Sr86 ratio of the Olentangy River decreased with increasing discharge from 0.7116 to 0.7088 while that of the Scioto River appeared to be constant at 0.7093 =±= 0.0003 within the precision of the measurement

Possible Contamination of the Sandusky River by Wastewater Discharge by Bucyrus, Ohio

Author Institution: Department of Geological Sciences, The Ohio State UniversityThe objective of this study was to determine changes in the chemical composition of water that result from its use by the town of Bucyrus in Crawford County, OH, and to document the effect of the discharge of wastewater on the quality of water in the Sandusky River. The results indicate that the wastewater is enriched in the major elements (Na, K, Mg, Ca, and Sr) compared to tap water in the town of Bucyrus. However, the treated wastewater does not significantly alter the chemical composition of water in the Sandusky River represented by a ten-year average from 1984 to 1994. The concentrations of Mo in raw water and in the wastewater are nearly identical, which means it cannot have an anthropogenic source. The wastewater does not contain P because this element is effectively removed as required by the Great Lakes Water Quality Agreement

Feldspar-Provenance Dates in a Stratigraphic Section of Till in Gahanna, Ohio

Author Institution: Department of Geology and Mineralogy and The Institute of Polar Studies, The Ohio State UniversityThe internal layering and provenance of feldspar in 3 tills and in one outwash deposit at Gahanna, Ohio, were studied by determining pebble lithologies and Rb-Sr dates of feldspar. Variations in lithology of pebbles and in the Rb-Sr ratios of feldspar in the 125—250 micrometer fractions reveal discontinuities which divide the upper 2 tills into 2 subunits each. Each of the lower subunits appears to be more homogeneous than the upper ones based on comparisons of standard deviations. This suggests the lower subunits may be basal or lodgement till and the upper subunits may be ablation till. Feldspar-provenance dates in till of the mid western United States are expressions of the proportion of mixing of feldspar grains originating from the Superior (2.7 b. y.) and Grenville (1.07 b. y.) structural provinces of the Canadian Precambrian Shield. The Rb-Sr dates of feldspar in the layers of till and outwash of the Gahanna section are so variable that average dates cannot be used to distinguish among them. The lack of systematic stratigraphic variation of provenance dates indicates the feldspars are heterogeneous mixtures of the two Precambrian components. Approximately 90% of the dates have values between 1.0 and 1.5 b.y., which demonstrates the dominance of feldspar derived from the Grenville Province. Four samples whose dates are less than 1.0 b. y. contain younger feldspar presumably derived from sandstone of late Paleozoic age

The Isotope Composition of Strontium and Cation Concentrations of Lake Vanda and Lake Bonney in Southern Victoria Land, Antarctica

"RF 2340" and "RF 2411"This report is based on a dissertation submitted by Lois M. Jones to the Graduate School of The Ohio State University.Second Annual Progress Report Grants GA-1713, GA-898X, submitted to the National Science FoundationThe ice-free valleys of southern Victoria Land are located in the Transantarctic Mountains west of Ross Island, Antarctica. In these valleys, the average annual temperature is well below the freezing point of water and precipitation is extremely low. Nevertheless, lakes are present and soils have begun to form since deglaciation. These lakes and soils are characterized by high concentrations of salts. The salinity of some lakes, such as Lake Vanda and Don Juan Pond in Wright Valley and Lake Bonney in Taylor Valley, is several times greater than that of sea water. In addition, salts occur as surface efflorescences and as lenses and cement within the soil. The origin of the salts in the lakes and soils of the ice- free valleys is controversial. Possible sources that have been suggested include: (l) trapped sea water; (2) wind-transported marine salts; (3) volcanic activity and associated hot springs; and (4) chemical weathering of local soil and bedrock. Previous attempts to explain the origin of the salts have resulted in conflicting conclusions because the parameters which were used (chemical composition, isotope composition of the water) have been modified by chemical or physical processes occurring in the lakes. In order to determine the origins of the salts, a new parameter is needed that can unambiguously identify a specific source for the salts. The isotopic composition of strontium in the salts meets the necessary requirements because: (1) the isotopic composition of strontium of each of the possible sources is distinctive and differs significantly from that of the other sources, and (2) the isotopes of strontium are not measurably fractionated in natural processes such as are occurring in the ice- free valleys. The objective of this study was to ascertain the usefulness of strontium isotopes as natural tracers, and to identify thereby the source(s) of the salts in the lakes and soils of the ice-free valleys in Antarctica. Lakes Vanda and Bonney were studied in detail because they are the largest and most unusual of the Antarctica lakes. Both lakes are perennially ice-covered and are meromictic. At depth the water is highly saline and has surprisingly high temperatures. Lake Vanda has a maximum density of 1.10 g/ml at a depth of 67 m, and a maximum recorded temperature of +28°C at the bottom of the lake. Lake Bonney has a maximum density of 1.20 g/ml at a depth of 32 m, and reaches a temperature of +8°C at about the middle of the depth profile. In order to determine the origin of the salts in the two lakes, measurements were made of the isotopic composition of strontium in water samples collected at different depths from the surface to the bottom of the lakes. The results of these analyses were then compared to isotopic compositions of strontium in sea water, basalts of the McMurdo volcanic province, and the strontium in water-soluble salts from the soils in Wright and Taylor Valleys. From these comparisons the principal sources of the strontium in the two lakes can be clearly identified. In addition to measurements of the isotopic composition of strontium in the lakes, chemical analyses of the brines have been made to provide information that can be used with the isotopic studies to develop a model for the geochemical evolution of the lakes. The combination of isotopic and chemical analyses of the brines in Lakes Vanda and Bonney permits the formulation of a better model than has been possible before.National Science Foundation Grants GA-713 and GA-898

Strontium Anomalies in Till of the Powell-Union City Moraine, Ohio

Author Institution: Department of Geology and Mineralogy, The Ohio State UniversityThe strontium concentration of till from the Powell-Union City Moraine varies with grain size and has maximum values in the —120 + 200 mesh (70— 125 /Jim) fractions. It correlates positively with the carbonate content of till but depends also on the presence of feldspar, clay and other minerals. The strontium content of —120 + 200 mesh fractions of 19 till samples collected along the Powell-Union City Moraine increases from about 100 ppm in central Ohio up to 220 ppm at the Indiana border. The increase coincides with a change in the lithologic composition of the bedrock from sandstone and shale (Mississippian and Devonian) to carbonate rocks (Devonian and Silurian). Two positive strontium anomalies were found at Fulton and Piqua that might be attributed to the presence of celestite (SrSO4) derived from the underlying bedrock. However, no celestite was found in the till samples. The excess strontium concentrations of samples in the Fulton anomaly correlate positively with their K-feldspar/plagioclase ratios and appear to be caused by a change in the mineralogical composition of feldspar rather than by an increase in the abundance of this mineral. The cause for the Piqua anomaly is unknown

Age Determination of a Granite Gneiss from the Precambrian Basement of Scioto County, Ohio

Author Institution: Department of Geology and Mineralogy, The Ohio State University, Columbus, Ohio 43210 and Ohio Division of Geological Survey, Columbus, Ohio 43212Biotite and potassium feldspar from a specimen of granite gneiss from the Precambrian basement of Scioto County (Permit No. 212, Greenup Quadrangle of Green Township) have been dated by the Rb-Sr method. The model dates, calculated relative to an assumed initial 87Sr/86Sr ratio of 0.7040, are 898±40 million years (biotite) and 1242±46 million years (potassium feldspar). The dates are discordant, which suggests that the minerals gained or lost rubidium and/or strontium during an episode of metamorphism. The age of the metamorphism is estimated as 840=t42 million years, assuming that both minerals were isotopically re-equilibrated and had the same 87Sr/86Sr ratio of 0.7178± 0.0026. The model date of the biotite agrees with previous age determinations of basement rocks from Ohio and confirms the interpretation that the Grenville Province of the Canadian Precambrian Shield extends southward into Ohio